In spite of the number of antibiotics available against a variety of bacteria, due to emergence of multiple drug resistant strains, the search for never and more effective antibacterial compounds has continued. 4,5-dihydroxy-2-cyclopenten-1-one (DHCP) (see FIG. 1) is a compound having antibacterial activity against a variety of gram-positive and -negative bacteria, such as Escherichia coli, Bacillu, Salmonella, Staphylococcus etc. The process for manufacture and the propeties of DHCP have been patented (Koyama et al. 1999). It is prepared by the heat-treatment of uronic acid or its derivatives, wherein uronic acid is galacturonic acid, glucuronic acid, mannuronic acid, or iduronic acid. It is also produced from roasted or parched vegetables, fruits, cereals, mushrooms, sea algae, cortex, or cartilage. It has been demonstrated that this compound induces cancer cell differentiation and apoptosis. It has potential application as therapeutic or preventative agent against cancer and also as an antibacterial agent in antiseptics, dentrifices, cosmetics, and bathing agaents (Koyama et al. 1999).
We have isolated a multicopy suppressor from an E. coli genomic library for the DHCP toxicity. The putative protein encoded by this gene showed high homology to known efflux proteins conferring resistance to a number of antibiotics including chloramphenicol, bicyclomycin, and tetracycline. The gene was mapped at 37.5 min on the E. coli chromosome. It is designated as dep for DHCP-efflux protein. However, the Dep protein does not confer cross-resistance to any of the antibiotics tested.